In case the slider equipped with the magnetic head is formed, normally such slider is formed via the steps of forming a plurality of magnetic heads in a matrix fashion on a substantially disk-like substrate, then dividing the substrate into a plurality of pieces to form Bar-like (stripe-like) works, then shaping the works, and then dividing the works into chips every magnetic head. The chip-like substrate is employed as the slider.
In the steps of shaping the work, steps of forming a rail surface for the slider and lapping a part of the work are contained. The bar-like work is also called a “row bar” on which at least the magnetic heads are aligned.
The lapping of the work is carried out to adjust a height of a magneto-resistive layer constituting the magnetic head and a height of the gap layer. Since the precision in the order of submicron unit is required for the height of the magneto-resistive layer or the gap layer, capable of working the work with high precision is needed.
In case the magnetic head is lapped, the lapping machine as set forth in Patent Application Publication (KOKAI) Hei 10-286765, for example, is employed.
As shown in FIG. 1, in case the work is lapped by the lapping machine, the work 101 is fitted to a lower surface of a lapping jig 102 in the situation that a top end of the magnetic head (not shown) on the work 101 is directed downward, and then the lapping jig 102 is fitted to an adaptor 103. Then, top ends of the work 101 and the magnetic head are lapped by a lapping surface plate 104. The work 101 is pushed against the lapping surface plate 104 by a pressure machine 105 via the adaptor 103 and the lapping jig 102. In addition, because the camber is generated in many works 101, all the magnetic heads on the work 101 are seldom brought into contact with an upper surface of the lapping surface plate 104 under the same conditions. For this reason, a lower end of the lapping jig 102 is pushed against the lapping surface plate 104 by one or three bending arms 106 that are passed through an opening 102a provided in the center of the lapping jig 102, and then a distribution of the pushing force to the lapping surface plate 104 on work 101 is adjusted by changing the pushing force, whereby the camber of the work 101 with respect to the upper surface of the lapping surface plate 104 is corrected.
Meanwhile, as shown in FIG. 1, in order to correct the camber of the work 101 by using one or three bending arms 106, top end positions of a plurality of magnetic heads being aligned on the work 101 must be successively changed along the work 101, as shown in FIG. 2. In other words, in the case of the state as shown in FIG. 2, the use of the bending arm 106 makes it easy to uniformize the lapping of a plurality of magnetic heads on the work 101. If the lapping of the top ends of the magnetic heads is carried out uniformly, characteristics of the lapping heads become constant.
However, in case the top ends of a plurality of magnetic heads aligned on the work 101 are arranged discontinuously as shown in FIG. 3(a), 3(b), it is difficult to correct the camber of the work 101 by using the bending arm 106. Thus, the characteristics of the magnetic heads on the work 101 after the lapping do not become uniform.
Such camber of the work 101 is generated by several causes. As the causes, for example, there are the alignment error generated when a plurality of magnetic heads are formed on one substrate by the thin film growing technology, or the alignment error of the mask employed to pattern the thin film on the substrate, or the minute undulation of the cutting surface generated when the works 101 are formed by cutting the circular substrate, or the chips generated by cutting the substrate, or the flatness difference of the work contact surface of the lapping jig 102, or the fine dusts that are present between the work 101 and the lapping jig 102, etc.
Also, as another problem, when the crown, the camber, or the twist, as shown in FIGS. 4(a) to 4(c), is generated in the shape after the work 101 is lapped, variation in a floating amount of the sliders obtained by dividing the work 101 or deterioration of the characteristics of the magnetic head is caused.